1. Field of the Invention
The present invention relates to a bar coating apparatus and a bar coating method. More specifically, the invention relates to the bar coating apparatus and the bar coating method that are capable of applying a desired amount of coating solution to an object to be coated.
2. Description of the Related Art
In order to apply a coating solution to an object to be coated such as a metal plate and to remove excessive coating solution from the object to be coated (so-called measurement), a bar coating apparatus 102 as shown in FIG. 23 is conventionally used.
The bar coating apparatus 102 has a columnar coating bar 106, which is arranged so as to contact with a coating surface (lower surface) of a metal plate 104 in a direction perpendicular to a conveyance direction of the metal plate 104 (direction of arrow F1), which is conveyed at a constant conveyance speed. The coating bar 106 rotates due to friction with the metal plate 104 at a peripheral speed equal to the conveyance speed of the metal plate 104. A coating solution 108 is raised by the rotation of the coating bar 106, and a bead 110 is arranged between a weir member 112 and the metal plate 104. Namely, the coating solution in the bead 110 is applied to the metal plate 104 and any excess coating solution is removed (measured) from the metal plate 104.
Plates of various thicknesses are used for the metal plate 104 as an object to be coated. However, with changes in the thickness of the metal plate 104, a clearance between the metal plate 104 and the weir member 112 also changes. As a result, the bead 110 becomes unstable, which causes difficulty in obtaining uniformly coated surface quality.
In addition, the metal plate 104 occasionally flaps vertically and ripples due to conveyance. For this reason, the contacted state between the metal plate 104 and the coating bar 106 cannot be maintained constantly, and the bead 110 occasionally becomes unstable. Particularly recently, the conveyance speed of the metal plate 104 tends to be increased, and thus the possibility of the bead 110 not maintaining stability increases due to the higher speed. When the bead 110 becomes unstable, for example, it becomes difficult to obtain a uniformly coated surface quality because a coating streak is caused by the disturbance of the bead 110.
Further, the instability of the bead 110 due to the increased conveyance speed of the metal plate 104 causes the generation of so-called entrained air (air that is trapped inside the coating solution at the time of coating), which can decrease the coated surface quality. When the clearance between the weir member 112 and the object to be coated (metal plate 104) is large, the effect of the entrained air upon the coating solution is particularly noticeable. Hence, the bead 110 has a tendency to become unstable, and that in turn causes difficulty in obtaining uniform coated surface quality.
Furthermore, factors such as increased conveyance speed of the plate, increased viscosity of the coating solution, and varying conditions at the time of coating can hinder maintenance of stability in the bead 110. Disturbance of the bead results in problems such as difficulty in obtaining uniform coated surface quality due to coating streaks and coating breakage.
In view of the above facts, an object of the present invention is to provide a bar coating apparatus and a bar coating method, which are capable of obtaining uniformly coated surface qualities by corresponding to the various thickness of the objects to be coated.
In addition, it is another object of the invention to provide a bar coating apparatus and a bar coating method which are capable of obtaining uniformly coated surface quality even if a conveyance speed of an object to be coated is increased or a viscosity of a coating solution is increased.
A first aspect of the invention is a bar coating apparatus comprising: a coating bar for contacting an object to be coated, which object is conveyed in a constant direction, so as to apply a coating solution to and remove excess coating solution from the object to be coated; a weir member for forming a bead of the coating solution between the object to be coated and the coating bar, the weir member being disposed upstream of the coating bar in a direction in which the object to be coated is conveyed; a pressing member for pressing the object to be coated from a side thereof opposite from the coating bar, the pressing member being disposed near the coating bar; and a moving device for moving the pressing member in a thickness direction of the object to be coated.
Further, in the first aspect, the pressing member is a pressing roll that is rotatingly driven by friction with the object to be coated.
Furthermore, in the first aspect, the bar coating apparatus further comprises a rotational drive for rotating the coating bar at a peripheral speed that differs from a peripheral speed corresponding to the speed at which the object to be coated is conveyed.
A second aspect of the invention is a bar coating method of bringing a coating bar into contact with an object to be coated, which object is conveyed in a constant direction, so as to apply a coating solution to and remove excess coating solution from the object to be coated, comprising the steps of: supplying the object to be coated; pressing, with a pressing member disposed near the coating bar, the object to be coated from a side thereof opposite from the coating bar; and moving, in correspondence to a coating state, the pressing member in a thickness direction of the object to be coated.
Further, in the second aspect of the invention, the coating bar is rotated at a peripheral speed that differs from a peripheral speed corresponding to the speed at which the object to be coated is conveyed.
In the bar coating apparatus according to the first aspect, the coating bar is brought into contact with the object to be coated, which is conveyed, and the coating solution is applied to the object to be coated. The object to be coated is pressed by the pressing member from the opposite side of the coating bar in the vicinity of the coating bar. The pressing member can be moved in a thickness direction of the object to be coated by the moving apparatus. Therefore, even if the objects to be coated have various thicknesses, the pressing member is moved, and the clearance between the object to be coated and the weir plate is adjusted, so that the bead of the coating solution formed among the weir member, the coating bar and the object to be coated can be stabilized. For this reason, a coated surface quality of the object to be coated is also stabilized, and even if the object to be coated has various thicknesses, the uniform coated surface quality can be obtained.
In addition, a member that merely contacts and presses the object to be coated may be used as the pressing member. However, when the pressing member is a pressing roll, which is driven to rotate by friction with the object to be coated, the object to be coated can be prevented from being rubbed and damaged by the pressing roll.
Further, when the coating bar is not rotated by the friction with the object to be coated, but is actively rotated by the rotation drive at a peripheral speed different from a peripheral speed corresponding to the conveyance speed of the object to be coated, the bead formed among the weir plate, the coating bar and the object to be coated can be stabilized. Therefore, for example, even in the case where the conveyance speed of the object to be coated is increased and the viscosity of the coating solution is increased, the uniform coated surface quality can be obtained.
In the bar coating method according to the second aspect, the coating bar is brought into contact with the object to be coated, which is conveyed, and the coating solution is transferred and applied to the object to be coated. The object to be coated is pressed from the opposite side of the coating bar by the pressing member in the vicinity of the coating bar, and the pressing member is moved in the thickness direction of the object to be coated according to a coating state. Therefore, the pressing member is moved in the thickness direction of the object to be coated in accordance to the various thickness of the object to be coated, so that the clearance between the object to be coated and the weir member is adjusted and the bead can be stabilized. For this reason, the coated surface quality of the object to be coated is also stable, and the uniform coated surface quality can be obtained even when the object to be coated has various thickness.
In addition, the coating bar is not rotated by friction with the object to be coated and the coating bar, but is actively rotated at a peripheral speed different from a peripheral speed corresponding to the conveyance speed of the object to be coated. As a result, the bead formed among the weir plate, the coating bar and the object to be coated can be stabilized. Therefore, for example, even in cases where the conveyance speed of the object to be coated is increased and the viscosity of the coating solution is increased, the uniform coated surface quality can be obtained.
A third aspect of the invention is a bar coating apparatus comprising: a coating bar for contacting an object to be coated, which object is conveyed in a constant direction, so as to apply a coating solution to and remove excess coating solution from the object to be coated; a weir member for forming a bead of the coating solution between the object to be coated and the coating bar, the weir member being disposed upstream of the coating bar in a direction in which the object to be coated is conveyed; and a pressing member for pressing the object to be coated from a side thereof opposite from the coating bar, the member being disposed near the coating bar.
Further, in the third aspect, the pressing member is a pressing roll that is rotatingly driven by friction with the object to be coated.
Furthermore, in the third aspect, the bar coating apparatus further comprises a rotational drive for rotating the coating bar at a peripheral speed that differs from a peripheral speed corresponding to the speed at which the object to be coated is conveyed.
A fourth aspect of the invention is a bar coating method of bringing a coating bar into contact with an object to be coated, which object is conveyed in a constant direction, so as to apply a coating solution to and remove excess coating solution from the object to be coated, comprising the steps of: supplying the object to be coated; and pressing, with a pressing member disposed near the coating bar, the object to be coated from a side thereof opposite from the coating bar.
Further, in the fourth aspect of the invention, the coating bar is rotated at a peripheral speed that differs from a peripheral speed corresponding to the speed at which the object to be coated is conveyed.
In the bar coating apparatus according to the third aspect, the coating bar is brought into contact with the object to be coated, which is conveyed, and the coating solution is applied to the object to be coated. The object to be coated is pressed by the pressing member from the opposite side of the coating bar in the vicinity of the coating bar. Therefore, flapping of the object to be coating during conveyance is prevented, and the bead of the coating solution formed among the weir member, the coating bar and the object to be coated is stabilized. For this reason, a coated surface quality of the object to be coated is also stabilized. Further, even if, for example, the conveyance speed of the object to be coated is increased, the uniform coated surface quality can be obtained.
In addition, a member that merely contacts and presses the object to be coated may be used as the pressing member. However, when the pressing member is a pressing roll, which is driven to rotate by friction with the object to be coated, the object to be coated can be prevented from being rubbed and damaged by the pressing roll.
Further, the coating bar is not rotated by friction with the object to be coated, but is actively rotated at a peripheral speed different from a peripheral speed corresponding to the conveyance speed of the object to be coated. As a result, the bead formed among the weir plate, the coating bar and the object to be coated can be stabilized. Therefore, for example, even in cases where the conveyance speed of the object to be coated is increased and the viscosity of the coating solution is increased, the uniform coated surface quality can be obtained.
In the bar coating method according to the fourth aspect, the coating bar is brought into contact with the object to be coated, which is conveyed, and the coating solution is transferred and applied to the object to be coated. The object to be coated is pressed from the opposite side of the coating bar by the pressing member in a vicinity of the coating bar. Therefore, the flapping of the object to be coated during conveyance is prevented, and the bead of the coating solution is stabilized. For this reason, the coated surface quality of the object to be coated is also stable. Further, even if, for example, the conveyance speed of the object to be coated is increased, the uniform coated surface quality can be obtained.
In addition, the coating bar is not rotated by friction with the object to be coated, but is actively rotated at a peripheral speed different from a peripheral speed corresponding to the conveyance speed of the object to be coated. As a result, the bead formed among the weir member, the coating bar and the object to be coated can be stabilized. Therefore, for example, even in cases where the conveyance speed of the object to be coated is increased and the viscosity of the coating solution is increased, the uniform coated surface quality can be obtained.
A fifth aspect of the invention is a bar coating apparatus comprising: a coating bar for contacting an object to be coated, which object is conveyed in a constant direction, so as to apply a coating solution to and remove excess coating solution from the object to be coated; a weir member for forming a bead of the coating solution between the object to be coated and the coating bar, the weir member being disposed upstream of the coating bar in a direction in which the object to be coated is conveyed; and a clearance-maintaining mechanism for maintaining clearance between the weir member and the object to be coated at a predetermined value of no more than 5 mm.
Further, in the fifth aspect, the bar coating apparatus further comprises a pressing member for pressing the object to be coated from a side thereof opposite from the coating bar, the member being disposed near the coating bar, wherein the clearance-maintaining mechanism comprises a moving device for moving at least one of the weir member and the pressing member in a thickness direction of the object to be coated.
Furthermore, in the fifth aspect, the bar coating apparatus further comprises a rotational drive for rotating the coating bar at a peripheral speed that differs from a peripheral speed corresponding to the speed at which the object to be coated is conveyed.
A sixth aspect of the invention is a bar coating method of bringing a coating bar into contact with an object to be coated, which object is conveyed in a constant direction, so as to apply a coating solution to and remove excess coating solution from the object to be coated, comprising the steps of: supplying the object to be coated; and forming a bead of the coating solution between the object to be coated and the coating bar with a weir member disposed upstream of the coating bar in a direction in which the object to be coated is conveyed, wherein clearance between the weir member and the object to be coated is maintained at a predetermined value of no more than 5 mm.
Further, in the sixth aspect, the coating bar is rotated at a peripheral speed that differs from a peripheral speed corresponding to the speed at which the object to be coated is conveyed.
In the bar coating apparatus according to the fifth aspect, the coating bar is brought into contact with the object to be coated, which is conveyed, and the coating solution is applied to the object to be coated. At this time, the bead of the coating solution is formed among the weir member, the coating bar and the object to be coated.
The clearance between the weir member and the object to be coated is maintained in a predetermined value of 5 mm or less by the clearance-maintaining mechanism. When the upper limit of the clearance is defined, the trapping of the entrained air is reduced (preferably, entrained air is not generated), so that the bead can be maintained stably. For this reason, the coated surface quality of the object to be coated is stabilized, and even in the case where the conveyance speed of the object to be coated is increased, the uniform coated surface quality can be obtained.
In addition, the weir member itself may be approached to and/or be separated from the object to be coated, or the pressing member may press the object to be coated and move the object to be coated so as to approach to and/or separate from the weir member.
Further, since the coating bar is not rotated by friction with the object to be coated, but is actively rotated by the rotation drive at a peripheral speed different from a peripheral speed corresponding to the conveyance speed of the object to be coated, the bead formed among the weir plate, the coating bar and the object to be coated can be stable. Therefore, for example, even in cases where the conveyance speed of the object to be coated is increased and the viscosity of the coating solution is increased, the uniform coated surface quality can be obtained.
In the bar coating method according to the sixth aspect, the coating bar is brought into contact with the object to be coated, which is conveyed, and the coating solution is transferred and applied to the object to be coated. At this time, the bead of the coating solution is formed among the weir member, the coating bar and the object to be coated.
Here, the clearance between the weir member and the object to be coated is maintained in a predetermined value of 5 mm or less. When the upper limit of the clearance is defined, the trapping of the entrained air is reduced (preferably, entrained air is not generated), and the bead can be maintained stably. For this reason, the coated surface quality of the object to be coated is stable, and even in the case where, for example, the conveyance speed of the object to be coated is increased, the uniform coated surface quality can be obtained.
In addition, since the coating bar is not rotated by friction with the object to be coated, but is actively rotated at a peripheral speed different from a peripheral speed corresponding to the conveyance speed of the object to be coated. As a result, the bead formed among the weir member, the coating bar and the object to be coated can be stabilized. Therefore, for example, even in cases where the conveyance speed of the object to be coated is increased and the viscosity of the coating solution is increased, the uniform coated surface quality can be obtained.
In the invention, the length of the clearance does not have a lower limit value from a viewpoint of reducing entrained air trapped in the coating solution. However, in order to prevent unnecessary contact of the weir member with the object to be coated, it is preferable that the length is maintained at 0.1 mm or more.
In addition, the xe2x80x9cdifferent periphery speedxe2x80x9d includes the case where the coating bar rotates in the same direction as the conveyance direction of the object to be coated and the case where the coating bar rotates in the opposite direction of the conveyance direction of the object to be coated.
A seventh aspect of the invention is a bar coating apparatus comprising: a coating bar for contacting an object to be coated, which object is conveyed in a constant direction, so as to apply a coating solution to and remove excess coating solution from the object to be coated; a weir member for forming a bead of the coating solution between the object to be coated and the coating bar, the weir member being disposed upstream of the coating bar in a direction in which the object to be coated is conveyed; and a rotational drive for rotating the coating bar at a peripheral speed that differs from a peripheral speed corresponding to the speed at which the object to be coated is conveyed.
Further, in the seventh aspect, the number of revolutions of the coating bar is within xc2x1500/min.
Furthermore, in the seventh aspect, the bar coating apparatus further comprises a switching mechanism for switching a rotational driving force of the rotational drive between a transmitting state, in which the driving force is transmitted to the coating bar, and a non-transmitting state, in which the driving force is not transmitted to the coating bar.
An eighth aspect of the invention is a bar coating method of bringing a coating bar into contact with an object to be coated, which object is conveyed in a constant direction, so as to apply a coating solution to and remove excess coating solution from the object to be coated, comprising the steps of: supplying the object to be coated; and rotating the coating bar at a peripheral speed that differs from a peripheral speed corresponding to the speed at which the object to be coated is conveyed.
Further, in the eighth aspect, the number of revolutions of the coating bar is within xc2x1500/min.
In the bar coating apparatus according to the seventh aspect, the coating bar is brought into contact with the object to be coated, which is conveyed, and the coating solution is applied to the object to be coated. In the bar coating apparatus, the coating bar is not rotated by friction with the object to be coated, but is actively rotated by the rotation drive so that its peripheral speed is different from a peripheral speed corresponding to the conveyance speed of the object to be coated. As a result, the bead of the coating solution formed among the weir member, the coating bar and the object to be coated can be stabilized. Therefore, for example, in cases where the conveyance speed of the object to be coated is increased and the viscosity of the coating solution is increased, the uniform coated surface quality can be obtained.
In addition, the number of revolutions of the coating bar is not particularly limited as long as its peripheral speed is different from a peripheral speed corresponding to the conveyance speed of the object to be coated. However, the number of revolutions of the coating bar is within xc2x1500/min, so that the bead can be securely stabilized.
Further, the rotational driving force of the rotation drive can be prevented from being transmitted to the coating bar by the switching mechanism. As a result, the coating bar can be rotated by friction with the object to be coated as the conventional structure.
In the bar coating method according to the eighth aspect, the coating bar is not rotated by friction with the object to be coated, but is actively rotated at a peripheral speed different from a peripheral speed corresponding to the conveyance speed of the object to be coated. As a result, the bead of the coating solution can be stabilized. Therefore, for example, even in cases where the conveyance speed of the object to be coated is increased and the viscosity of the coating solution is increased, the uniform coated surface quality can be obtained.
In addition, the number of revolutions of the coating bar is not particularly limited as long as its peripheral speed is different from a peripheral speed corresponding to the conveyance speed of the object to be coated as mentioned above. However, when the number of revolutions of the coating bar is within xc2x1500/min, the bead can be securely stabilized.
The xe2x80x9cnumber of revolutionxe2x80x9d is indicated by xe2x80x9c+xe2x80x9d when the contact portion of the coating bar with the object to be coated moves in the same direction as the conveyance direction of the object to be coated. Therefore, when the number of revolutions is indicated by xe2x80x9cxe2x88x92xe2x80x9d, the contact portion of the coating bar with the object to be coated moves in the opposite direction of the conveyance direction of the object to be coated.